The J-11B is the first of the Shenyang ‘Sino-Sukhoi’ family to have been developed independently without Russian assistance. The aircraft resembles the Su-27SK ‘Flanker-B’ in appearance and is also powered by two Russian AL-31F engines initially, but is equipped with Chinese avionics and weapons. A two-seat fighter trainer variant designated J-11BS has also been introduced, which appears to be a direct copy of the Su-27UBK ‘Flanker-C’.

When the licensed production of the Su-27SK under the designation J-11 began at SAC in 1998, the PLAAF was already in the process of seeking a more advanced fighter to succeed this Cold War-era design. Sukhoi was originally trying to sell the PLAAF the Su-27SMK, an upgraded multirole variant of the Su-27 capable of firing the active radar-homing missile and a range of precision-guided weapons. However, the PLAAF declined the offer in favour of an indigenous design due to its concern over excessive reliance on a foreign supplier.

SAC unveiled in mid-2002 that it was developing a multirole fighter by incorporating the Su-27/J-11 airframe with Chinese-made avionics and weapon systems. The licensed production of the Su-27SK using Russian-supplied kits stopped in 2003 after about 100 examples had been produced (out of 200 stipulated in the original contract). SAC subsequently began to build the J-11 airframes independently, possibly through reverse-engineering and without Russian consent.

The Chinese-built J-11B, still powered by Russian AL-31F engines, was introduced in 2004. The two-seat J-11BS was introduced three years later in 2007. Both have been in service with the PLAAF since 2007. The PLA Naval Air Force (PLANAF) also received the naval variant designated J-11BH and J-11BSH.

Design

The J-11 is almost identical to the Su-27SK/UBK externally, with mid-mounted and semi-delta wings with square tips. The leading-edge extension (LERX) extends downward and forward of the wing roots, with two rectangular air intakes underneath the fuselage and a large tail boom. The tail fins are swept-back, tapered with square tips, and mounted outboard of the engines. The horizontal stabilisers are mid-mounted, swept-back, and tapered. The nose is pointed with a bubble-shaped canopy.

Avionics

The J-11 features an avionics suite that is completely Chinese-developed. Its Pulse-Doppler fire-control radar is capable of tracking 6—8 targets and engaging with 4 of them simultaneously.

An electro-optical targeting system (EOTS), believed to have been based on the Russian OEPS-27 design found on the Su-27, is located in front of the cockpit. The system comprises an infrared search and track (IRST) sensor and a laser rangefinder, and is used to detect enemy targets passively without requiring to turn on the fire-control radar, thus reducing the chance of the aircraft being detected.

Armament

Just like the Su-27SK/UBK, the J-11 is primarily designed for air superiority role, with ground attack as a secondary mission. It does not have the capability to deliver precision-guided munitions.

Fixed weapon include a Chinese indigenous 30-mm internal cannon with 150 rounds. Up to 4,430 kg weapon load can be carried on 10 external stores hardpoints, including 2 tandem under the fuselage centreline, 2 under the air ducts, 4 under the wings, and 2 on the wingtips.

The naval variant J-11BH may also be able to carry the YJ-83K anti-ship cruise missile.

Engines

The early batch production variant of the J-11 was powered by two Lyulka-Saturn AL-31F turbofan engine, each rate at 75.22 kN (7,670 kgf, 16,910 lbf) dry and 122.6 kN (12,500 kgf, 27,560 lbf) with afterburning. The aircraft cannot receive in-flight refuelling.

SAC has been seeking to replace the AL-31F engines with the indigenously developed WS-10 Taihang turbofan (120—140 kN with afterburning). However, poor reliability of the Chinese engines forced SAC to continue relying on Russian-made engines to power the J-11B. It appears that the technical issues with the WS-10 had been finally resolved by 2010, and later batches of the J-11B have been fitted with Chinese engines.